Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Sep. 30, 2020

Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]

Schedule of Changes in Accumulated Other Comprehensive Income (Loss) by Component

Changes in accumulated other comprehensive income (loss) by component were as follows (in millions):

	Employee Pension and Postretirement Benefits, Net of Tax			Cumulative Translation Adjustments			Derivative Instruments, Net of Tax			Accumulated Other Comprehensive Income (Loss)
Balance at September 30, 2017	$	(46.2	)	$	(78.6	)	$	(0.2	)	$	(125.0	)
Other comprehensive income (loss) before reclassifications		33.1			(17.6	)		0.6			16.1
Amounts reclassified from accumulated other comprehensive income (loss)		2.2			—			(0.1	)		2.1
Net current period other comprehensive income (loss)		35.3			(17.6	)		0.5			18.2
Balance at September 30, 2018		(10.9	)		(96.2	)		0.3			(106.8	)
Tax impact of U.S. tax reform on Accumulated Other Comprehensive Income (ASU 2018-02)		(9.1	)		—			—			(9.1	)
Balance at October 1, 2018		(20.0	)		(96.2	)		0.3			(115.9	)
Other comprehensive income (loss) before reclassifications		(49.5	)		(36.3	)		—			(85.8	)
Amounts reclassified from accumulated other comprehensive income (loss)		0.1			—			—			0.1
Net current period other comprehensive income (loss)		(49.4	)		(36.3	)		—			(85.7	)
Balance at September 30, 2019		(69.4	)		(132.5	)		0.3			(201.6	)
Other comprehensive income (loss) before reclassifications		(29.3	)		30.4			(0.5	)		0.6
Amounts reclassified from accumulated other comprehensive income (loss)		2.8			—			(0.2	)		2.6
Net current period other comprehensive income (loss)		(26.5	)		30.4			(0.7	)		3.2
Balance at September 30, 2020	$	(95.9	)	$	(102.1	)	$	(0.4	)	$	(198.4	)

Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Loss) Included in the Computation of Net Periodic Pension and Postretirement Benefit Cost

Reclassifications out of accumulated other comprehensive income (loss) included in the computation of net periodic pension and postretirement benefit cost (See Note 5 of the Notes to Consolidated Financial Statements for additional details regarding employee benefit plans) were as follows (in millions):

	Classification of	Fiscal Year Ended September 30,
	income (expense)	2020			2019			2018
Amortization of employee pension and postretirement benefits items
Prior service costs	Miscellaneous, net	$	0.7		$	0.2		$	0.9
Actuarial (gains) losses	Miscellaneous, net		3.1			—			2.0
Total before tax			3.8			0.2			2.9
Tax benefit			(1.0	)		(0.1	)		(0.7	)
Net of tax		$	2.8		$	0.1		$	2.2